95 chevy 350 no spark

[Stewman84]

Back story. Had issues with TBI, rebuilt. Had some starting problems after truck sat for 1 day or more, but would start after a few tries. At one point when it was particularly stubborn, starter lead vibrated off. Once reconnected, truck started, ran fine, but had some electrical humming & radio interference. The starting issue continued with some low rpm stumbling, when driving check engine light would come on at cruising speeds and go off 7-8 seconds after letting off gas. Had 1 day lest week when I drove a bit more then normal (150+) but ran fine other then engine light. Next day started, but ran horribly rough with violent back fires. At one point stalled and would not restart. It looked and acted like it was flooding itself out and poor spark. Less then a year I replaced cap, rotor and coil. Now I have done all new plugs and wires. Now it appears I have no spark. I had been in the dash messing with the blower motor relay 2 days prior to the stalling and not starting.
Does the ECM control spark? Cant it go bad slowly? And if I had to do alot of cranking of the engine to get it to start, would that have any thing to do with it going bad?
I am no mechanic, but I did stay at a Holiday Inn suites recently.

[j cAT]

since its this old replace the ICM. ign cont module. remove and have this tested at an auto zone most have the WELLS module tester.

make sure the distrib is good. the bearings are not worn. rotor does not rotate too much.

check that the CPS is still solidly mounted. remove and inspect clean / reinstall. check the wiring connections/connector.

[Stewman84]

Update. Got spark, am now going to replace Temp sensor later today. Was hard starting (I think) because temp sensor is bad and dumping too much fuel into tbi and flooding out.
Thanks.
ICM is good. If problems still, where is the cps, (pass side topside of engine?) and how do I test it?
Got temp sensor replaced, still wont start. Checked for 5 volts going to MAP sensor and reads correctly. Taking MAP sensor to be tested, will up date.
Side note, with battery charger on, it does not seem to be cranking very strong. Got 12v at battery. Afraid I got some ground issues some place.

[Schurkey]

Originally Posted by Stewman84

when driving check engine light would come on at cruising speeds and go off 7-8 seconds after letting off gas.

So what was the code that was set?

[Stewman84]

Originally Posted by Schurkey

So what was the code that was set?

Never was able to check codes, so I dont know.

[j cAT]

Originally Posted by Stewman84

Never was able to check codes, so I dont know.

the ect engine temp sensor may be the reason of the engine flooding out. you had no spark and cranked the engine . if you did this alot then the plugs may be fouled.

I would remove a plug see whats up. if its wet remove plugs disable fuel pump crank engine to blow out the fuel. then install cleaned or new plugs try again.

[Schurkey]

Originally Posted by Stewman84

Never was able to check codes, so I dont know.

You can throw money at parts, but you won't do appropriate diagnosis first. Not an efficient way to fix cars.

[DeltaP]

Like throwing darts at a dart board.

[j cAT]

Originally Posted by Stewman84

Never was able to check codes, so I dont know.

the code checking is a good way to properly find the area of failure or improper operation. it is true that most times it will not give you detailed repair instructions ,but will get you in the correct direction to troubleshoot the issue.

you also need a repair manual. these forums are to help those with these tools. then the info gathered here can help members like you fix this old beater vehicle.

I suspect most of the parts you threw at it needed replacing anyway.

its almost an antique now.

[Stewman84]

Originally Posted by j cAT

the code checking is a good way to properly find the area of failure or improper operation. it is true that most times it will not give you detailed repair instructions ,but will get you in the correct direction to troubleshoot the issue.

you also need a repair manual. these forums are to help those with these tools. then the info gathered here can help members like you fix this old beater vehicle.

I suspect most of the parts you threw at it needed replacing anyway.

its almost an antique now.

I have the Haynes repair manual. Not a beater is actually in good shape. It is dead in the driveway now and I cannot find a code reader. I am sure not [u]all[u] members have all the tools needed. I am a construction manager and carpenter.

I do appreciate the input I am getting along with some patience, my frustration level is way up so please bare with me.

I check the MAP sensor and found it to be bad. Replaced it. I checked the TPS, it also seems to be bad. I get 5v from the connector, but when I back probe I got nada. I have one screw out, however it would seem some one may have tried to change it in the past, the other screw is rounded out. Any constructive input for that. Is there a easy out for what looks like and 8 size screw? I tried a cutting wheel on it to use a slotted screw driver, but no luck. Soaking in PB blast at the moment.

[j cAT]

well I never said you need all the tools to work this problem. you do however need a manual, code reader, volt ohm meter , and the ability to read and understand the wirng diagrams.

what you need to find out is why it does not start after that then you must decide how to proceed like do I do it or a repair shop.

The MAP could cause a no start issue If you tested it and its bad just disconnect it and see if it starts.

the TAC I would not mess with . this is checked by measuring the resistance when the throttle is moved.this would not cause a no start.

so how did you detemine that the MAP ids defective ?

once again something is wrong here you have too many failed components . you say its in good shape ?

[tempfixit]

retrieving codes without a code reader, should also be in the haynes manual also. This is from repair help section of autozone.com


1988-95 MODELS




See Figures 1 and 2
Listings of the trouble for the various engine control system covered here are located in this section. Remember that a code only points to the faulty circuit NOT necessarily to a faulty component. Loose, damaged or corroded connections may contribute to a fault code on a circuit when the sensor or component is operating properly. Be sure that the components are faulty before replacing them, especially the expensive ones.





Fig. Fig. 1: ALDL connector-1988-92 models

The Assembly Line Diagnostic Link (ALDL) connector or Data Link Connector (DLC) may be located under the dash and sometimes covered with a plastic cover labeled DIAGNOSTIC CONNECTOR.

1. The diagnostic trouble codes can be read by grounding test terminal B. The terminal is most easily grounded by connecting it to terminal A (internal ECM ground). This is the terminal to the right of terminal B on the top row of the ALDL connector.
2. Once the terminals have been connected, the ignition switch must be moved to the ON position with the engine not running.
3. The Service Engine Soon or Check Engine light should be flashing. If it isn't, turn the ignition OFF and remove the jumper wire. Turn the ignition ON and confirm that light is now on. If it is not, replace the bulb and try again. If the bulb still will not light, or if it does not flash with the test terminal grounded, the system should be diagnosed by an experienced driveability technician. If the light is OK, proceed as follows.
4. The code(s) stored in memory may be read through counting the flashes of the dashboard warning lamp. The dash warning lamp should begin to flash Code 12. The code will display as one flash, a pause and two flashes. Code 12 is not a fault code. It is used as a system acknowledgment or handshake code; its presence indicates that the ECM can communicate as requested. Code 12 is used to begin every diagnostic sequence. Some vehicles also use Code 12 after all diagnostic codes have been sent.

Fig. Fig. 2: ALDL connector-1993-95 models

1. After Code 12 has been transmitted 3 times, the fault codes, if any, will each be transmitted 3 times. The codes are stored and transmitted in numeric order from lowest to highest.

The order of codes in the memory does not indicate the order of occurrence.

1. If there are no codes stored, but a driveability or emissions problem is evident, the system should be diagnosed by an experienced driveability technician.
2. If one or more codes are stored, record them. Refer to the applicable Diagnostic Code chart in this section.
3. Switch the ignition OFF when finished with code retrieval or scan tool readings.

[Stewman84]

Check and replaced MAP sensor. Checked ICM, checked out fine. Checked TPS has proper voltage both at the connector, as well as when throttle engages while back probing.
However, at last try I turned the key and got NOTHING, no click, no crank, NOTHING. Yes I had lights radio ect. I have had my battery charger connected alot since I have been running this shit down.
I am pulling the starter and the battery both today to have them tested. I am at my wits end on this.

Stew

[Stewman84]

My inexperience here is kicking my ass. Still not cranking, no "click" even at the starter. Pulled and checked stater, its fine. I checked for 12V at the small (ignition?) wire, and didn't have it. Went to the engine compartment fuse relay box, and had the 12V.

My question is, the smaller wire coming off the starter goes where? I am some what certain that it has a break in it. I cut the last 6" off because it looked crappy. But from there I cannot find where it goes. Does it go directly to the fuse relay box? I took new wire and went from fuse relay to starter, but it did not work. Help.

PS I did check all the fuses in the relay first.

[MT-2500]

Originally Posted by Stewman84

My inexperience here is kicking my ass. Still not cranking, no "click" even at the starter. Pulled and checked stater, its fine. I checked for 12V at the small (ignition?) wire, and didn't have it. Went to the engine compartment fuse relay box, and had the 12V.

My question is, the smaller wire coming off the starter goes where? I am some what certain that it has a break in it. I cut the last 6" off because it looked crappy. But from there I cannot find where it goes. Does it go directly to the fuse relay box? I took new wire and went from fuse relay to starter, but it did not work. Help.

PS I did check all the fuses in the relay first.

AT transmission IT GOES FROM STARTER TO NEUTRAL SAFTEY SWITCH.
Usually purple wire.
From saftey switch it goes to ign switch.

STD transission there is a clutch saftey switch between starter and ign switch.